#include <cstdio>
#include <cstring>

void work( char a[] )
{
    int i, len = strlen( a );
    char tmp;
    for ( i = 0; i < len / 2; i++ )
    {
        tmp = a[ i ];
        a[ i ] = a[ len - i - 1 ];
        a[ len - i - 1 ] = tmp;
    }
    for ( i = len - 1; i > 0 && a[ i ] == 'A'; i-- )
        a[ i ] = 0;
}

int main( )
{
    char a[ 201 ], b[ 201 ];
    int i, len1, len2;
    while ( scanf("%s%s", a, b) != EOF )
    {
        work( a );
        work( b );
        len1 = strlen( a );
        len2 = strlen( b );
        for ( i = len1; i < len2; i++ )
            a[ i ] = 'A';
        if ( len1 < len2 )
            len1 = len2;
        for ( i = 0; i < len2; i++ )
            a[ i ] += b[ i ] - 'A';
        for ( i = 0; i < len1; i++ )
            if ( a[ i ] > 'Z' )
            {
                if ( i == len1 - 1 )
                {
                    a[ i + 1 ] = 'A';
                    len1++;
                }
                a[ i + 1 ]++;
                a[ i ] -= 26;
            }
        for ( i = len1 - 1; i >= 0; i-- )
            putchar( a[ i ] );
        printf("\n");
    }
    return 0;
}
